1. Field of the Invention
The present disclosure relates to a technology of suppressing entering of leakage magnetic field noise, generated from a magnetic field generation source, into an image pickup element.
2. Description of the Related Art
Recently, an image pickup element mounted on an imaging device such as a digital camcorder or a digital still camera has higher ISO sensitivity. As such, a clearer image can be taken even in a scene of few light quantities such as night view. Along with improvements in sensitivity, however, an image pickup element is affected by weak noise which has not been a problem, whereby a problem of disturbance caused in an image is becoming apparent.
For example, in a digital single lens reflex camera, an interchangeable lens includes a coil provided inside a motor circuit for driving the lens. A slight amount of leakage magnetic flex generated from such a coil may affect the image pickup element to thereby cause disturbance of an image to be generated.
Conventionally, Japanese Patent Application Laid-open No. 2011-123432 proposes that in order to shield a magnetic field from a magnetic field generation source located around an image pickup element, part of the image pickup element is surrounded by a ferromagnetic substance having high relative permeability such as permalloy.
A plate member of a ferromagnetic substance having high relative permeability (such as permalloy, for example) exhibits a high magnetic field shielding effect if the surface area is large. However, it is expensive compared with stainless or steel sheet generally used for casings of electronic devices. As such, for inexpensive products, it is not allowable to use an effective, large ferromagnetic substance having high relative permeability. As such, it is desirable to have a configuration capable of effectively reducing the amount of a magnetic field reaching an image pickup element, even if the area of a ferromagnetic material having high relative permeability is small.
In view of the above, an object of the present technology is to reduce the amount of a magnetic field reaching an image pickup element even if the area (cubic content) of a magnetic body, made of a ferromagnetic material having high relative permeability, is small.